KEVOS® MAKEOS · Fabrication
Guillotine Shearing Force
What force does it take to shear this sheet or plate, and can the shear do it?
Shearing force for straight parallel blades or inclined (raked) blades, including the machine allowance, compared with the shear’s rated capacity.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Blades | choice | Parallel blades (croppers, punch-shears) or inclined blades (guillotines). |
| Material thickness | mm | Sheet or plate thickness. |
| Cut length (parallel blades) | mm | Length of the cut for parallel blades. |
| Tensile strength | MPa | Ultimate tensile strength of the material from its certificate. |
| Shear strength ÷ tensile strength | Shear strength as a fraction of tensile strength (about 0.7–0.8 for steels). | |
| Blade rake angle | ° | Rake angle of the upper blade (inclined blades). |
| Relative blade penetration at fracture | Fraction of the thickness the blade penetrates before fracture, from the material table (softer materials penetrate more). | |
| Inclined blade factor n | Factor for inclined blades, about 0.75–0.85 for most materials. | |
| Shear rated capacity | kN | Rated force of the shear from its plate or manual. |
Method and formulas
- Parallel blades: F = τ × b × t, with τ = ratio × UTS; machine force = 1.3F.
- Inclined blades: F = n × k × UTS × λ × t² ÷ tan φ, with k the shear ratio, λ the relative penetration and φ the rake angle.
- Example: 6 mm plate of 450 MPa with a 2° rake needs about 118.76 kN.
Limitations
- Blade clearance, dull blades and thickness variation raise the force; the 30% allowance covers typical cases only.
- Rated capacity on a shear is usually stated for mild steel of a given strength; scale for stronger materials.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check whether a shear can cut a plate
- Compare rake angles
- Estimate force for flat bar cropping
Who it is for
- Fabrication supervisors
- Manufacturing engineers
- Estimators
What you get
- Shearing force
- Machine force with allowance
- Utilisation of the shear capacity
Interpreting the result
- Use the machine’s stated maximum thickness for the material strength as well as the force check.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1336–1339. Topic reference; no source tables or recommended settings are reproduced.
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